CARDIFF, WALES - MARCH 31: Anthony Joshua and his trainer Rob McCracken pose with his belts after during there WBA, IBF, WBO & IBO Heavyweight Championship title fight at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

Anthony Joshua v Joseph Parker - World Heavyweight Title Fight

CARDIFF, WALES - MARCH 31: Anthony Joshua and his trainer Rob McCracken pose with his belts after during there WBA, IBF, WBO & IBO Heavyweight Championship title fight at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

CARDIFF, WALES - MARCH 31: Anthony Joshua shakes hands with a member of Team Parker after his WBA, IBF, WBO & IBO Heavyweight Championship title fight against Joseph Parker at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Julian Finney/Getty Images)

CARDIFF, WALES - MARCH 31: Anthony Joshua shakes hands with members of the crowd winning his WBA, IBF, WBO & IBO Heavyweight Championship title fight against Joseph Parker at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

Anthony Joshua v Joseph Parker - World Heavyweight Title Fight

CARDIFF, WALES - MARCH 31: Anthony Joshua and members of his team pose with his belts after during there WBA, IBF, WBO & IBO Heavyweight Championship title fight at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

CARDIFF, WALES - MARCH 31: Anthony Joshua and his promoter Eddie Hern pose with his belts after during there WBA, IBF, WBO & IBO Heavyweight Championship title fight at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

CARDIFF, WALES - MARCH 31: Anthony Joshua and his Dad, Robert Joshua pose with his belts after during there WBA, IBF, WBO & IBO Heavyweight Championship title fight at Principality Stadium on March 31, 2018 in Cardiff, Wales. (Photo by Richard Heathcote/Getty Images)

Anthony Joshua v Joseph Parker Weigh In

CARDIFF, WALES - MARCH 30: Anthony Joshua (L) and Joseph Parker (R) at the weigh-in at the Motorpoint Arena on March 30, 2018 in Cardiff, Wales. Anthony Joshua will fight Joseph Parker in a heavyweight unification match at the Principality Stadium in Cardiff on March 31. (Photo by Matthew Horwood/Getty Images)

Anthony Joshua v Joseph Parker Weigh In

CARDIFF, WALES - MARCH 30: Anthony Joshua poses for the cameras during the weigh-in at the Motorpoint Arena on March 30, 2018 in Cardiff, Wales. Anthony Joshua will fight Joseph Parker in a heavyweight unification match at the Principality Stadium in Cardiff on March 31. (Photo by Matthew Horwood/Getty Images)

Anthony Joshua v Joseph Parker Weigh In

CARDIFF, WALES - MARCH 30: Anthony Joshua (L) and Joseph Parker (R) weigh-in at the Motorpoint Arena on March 30, 2018 in Cardiff, Wales. Anthony Joshua will fight Joseph Parker in a heavyweight unification match at the Principality Stadium in Cardiff on March 31. (Photo by Matthew Horwood/Getty Images)